Electrolytic apparatus.



1. PFLEGER & F. OTT. 1 ELECTROLYTIC APPARATUS.

I6, 1913. 1,186,936. Patented June 13, 1916.

AmRNBY 36m PFLEGER AND FRIEDRICH OTT, OE ERAN'KFORT-ON-THE-MAIN, GERMANY,

PATENT OFFICE.

ASSIG-NORS TO THE ROESSLEB 84 HASSLACHER CHEMICAL 00., OENEW YORK, N. Y.,

A. GOBPO -1TION OF NEW YORK.

ELECTROLYTIC APEARATUS.

Specification of Lettersjatent. Pat t d J 13 1915 Application filed June 16, 1913.; Serial No. 774,039.

To all whom it may concern:

Be it known that we, JoHANNns Prnnonn and FRIEDRICH Orr,- both subjects of the Emperor of Germany, and both residents of Frankfort-on-the-Main, Germany, have invented certain new and useful Improvements in Electrolytic Apparatus, of which the following is a specification.

This invention relates to an improvement in'electrolytic apparatus for the production of alkali metal, such as metallic sodium, from molten alkali halogenids, such as sodium chlorid, and it refers particularly to the protection of an essential part of the apparatus against the harmful action of the halogen, such as chlorin gas, generated in the process.

The well known apparatus of Castner for the production of alkali metal by electrolyzing fused alkali at a temperature only slightly above the melting point of the alkali, as described in United States Patent No. 452,030, German Patent No. 58,121, etc., operates satisfactorily, but the high price of the raw material usedis a handicap for the-production oi the metal at a lower pricethan at present, and if one selects cheaper substitutes for Castners-raw material precautions must be taken that such substitute shall form no products at the anode during the electrolysis which might attack the apparatus, such as chlorin gas for example.

The essential characteristics of the Castner process include the following: (1') the use of a wire net as a diaphragm; (2) the step of bringing the alkali metal separated by the electrolytic process, out of contact with the cathode. Attempts have been made to apply these essential characteristics of the Castner apparatus also to the electrolysis of alkali halogenids, such as sodium chlorid. This roblem was solved, according to German A atentNo. 236,804, by using two partitions separated from each other, made from difierent materials, difierently formed and located at certain places in the apparatus for the separation of the products by the electrolysis. Such an arrangement represents, however, only a complication of the Castner apparatus and of the method of operating the same.

We have now found that the complication, pointed out above, is not at all necessary in making said apparatus suitable for the electrolysis of alkali halogenids. This recogmtlon is based on the surprising observation that there is no other hindrance to the application of the Castner apparatus to the electrolysis of said alkali-halogenids but the fact that the outside of the vessel of the apparatus, which serves as a collector for the alkali metal generated by the electrolysis and furthermore brings the alkali metal out of contact with the cathode, is eX- posed to the destroying action of the halogen, such as chlorin, generated at the anode, and that one may easily and economically electrolyze alkali halogenids without the inconvenient means and steps shown by German Patent No. 236,804, if one covers the collector with a coat of halogen-proof or, in the case of the electrolysis of an alkali chlorid, of chlorin-proof material, down to p; somewhat below the level of the electroe. For the better understanding of our invention, reference is made to the accompanying drawing, which represents a sectional elevation of a convenient form of apparatus for carrying our invention into efiect.

The apparatus comprises a receptacle A, of iron or any other suitable material, which serves as a container for the electrolyte as well as for the electrodes with the other appurtenances necessary thereto The cathode 1, of iron or any other suitable material, is

entered preferably from below through the bottom of A and extends upward into the vessel from which it is suitably insulated.

The anode 2, preferably made of carbon, is

lower end is opposite to that of cathode l;

"he electrodes 1 and 2 are separated by a wire screen 3 which is connected with an iron receptacle 4:, the upper end of which is closed by a lid. a

The electrolyte reaches somewhat below the rim of vessel A and leaves ample space between anode and receptacle 4 into which the chlorin gas escapes. The outside of the receptacle 4 which is exposed to said chlorin gas is covered with a layer 5, made of material resistant to chlorin, said layer reaching somewhat below the level of the electrol e. Inside receptacle 4 the level of the e ectrolyte is somewhat higher than outside,

- either by dipping same out or by providing a contrivance for the drainage of-said metal.

Such a Castner apparatus, if provided with a protective coat on the outside of the collector as pointed out above, becomes a universal apparatus for the electrolytical roduction of alkali metals, as this modified astner apparatus does not require one to pay attention to harmful anode-products and thus permits the use of cheap raw materials. y

The protection of the vessel, acting as a collector for the sodium, in the electrolysis of sodium chlorid, against the action of the chlorin' is illustrated by the following examplershowing one of the ways by which we carry our invention into effect. I

.Asbestos-thread is impregnated with a thin paste-like mixture of water glass and asbestos-flour, and is then wound around the vessel, and is ready for use when dried. We do not restrict ourselves to the use of any particular halogen-proof material or to the practice of the process carried out in connection therewith with any particular alkali o as obtained by the process. The chlorin .halogen, further than the scope of the appended claims demands.

What we claim and desire to secure by Letters Patent is:

1. In an apparatus for the electrolysis of fused alkali salts, the combination with positive and negative electrodes having their working faces in close juxtaposition to each other, of a gauze or screen interposed between said electrodes, a superposed vessel or dome for receiving the separated metal and a halogen-resisting coating on the outer ing witnesses.

J OHANNES PFLEGER. FRIEDRICH OTT. Witnesses:

THos. A. ZIEGLER, CARL KIEFERTHAL. 

